SlWRKY22 and SlWRKY25 are positive regulators of plant immunity

RAMOS, ROMINA NAHIR; NING ZHANG; MARTIN, GREGORY; POMBO, MARINA ALEJANDRA; ROSLI, HERNÁN GUILLERMO

Virtual

Congreso; XXXIII RAFV; 2021

Plants defend themselves against pathogens using a two-layered immune system. Pattern-triggered immunity (PTI) is activated upon recognition of microbe-associated molecular patterns, such as flg22 epitope from flagellin. Virulent bacteria as Pseudomonas syringae pv. tomato (Pst), can deliver effector proteins into the plant cell to promote susceptibility. However, some plants possess resistance proteins that recognize specific effectors leading to the activation of effector-triggered immunity (ETI). Resistant tomatoes such as Río Grande-PtoR recognize two Pst effectors (AvrPto and AvrPtoB) through Pto/Prf complex, activating ETI.Previously, we found that WRKY22 and WRKY25 transcription factors (TF) participate in plant immunity against bacterial and non-bacterial pathogens in Nicotiana benthamiana. Using CRISPR-Cas9, we generated 3 tomato lines to knock-out these TFs (simple and double mutants). Higher Pst DC3000 ∆avrPto∆avrPtoB titers and reduced callose deposition associated to PTI induction, were observed in knock-out plants. We found that both SlWRKY22 and SlWRKY25, have a nuclear localization. Transcript abundance analysis, indicated that SlWRKY22 is induced earlier than SlWRKY25, suggesting a possible co-regulation, considering both genes have predicted WRKY binding sites (W-box) in their promoter regions.We identified a set of genes with expression patterns most similar to SlWRKY22-25 and selected those with W-box in their promoter regions. Out of 7 candidates, we found 1 that was induced by ETI in wild type but not in double mutant plants, indicating this could be a gene participating downstream of the TFs understudy.Our results confirm the involvement of both WRKY TFs in plant immunity and contribute to identifying components acting downstream.